Prior art furnace structure such as portable furnace structure for use with bottled liquid propane is indicated by the U.S. Pat. No. 3,590,806, with a gas heater in U.S. Pat. No. 3,846,616 indicated for use as a portable gas heater arrangement, with U.S. Pat. No. 3,689,040 indicating a portable space heater and gas burner utilizing a high-velocity air stream from within the gas burner structure. U.S. Pat. No. 4,512,328 sets forth a portable gas heating unit useful for heating food and the like.